Interchange Fourth Edition is a four-level series for adult and young-adult learners of English from the beginning to the high-intermediate level. Interchange Fourth Edition Full Contact B with Self-study DVD-ROM, Intro includes units 9-16 of the Student's Book, Workbook, and video worksheets, as well as the Self-study DVD-ROM. The DVD-ROM contains supplementary exercises. The corresponding Audio CDs are only sold separately.